Tension-based non-pneumatic tire

ABSTRACT

A non-pneumatic tire for supporting a load by working in tension comprising a generally annular inner ring, a generally annular outer ring, and an interconnected web having a plurality of web elements and comprising a plurality of generally polygonal openings. Web elements are sized, curved, oriented, and comprised of varying thicknesses of material which facilitates buckling when subjected to a compressive load. By buckling, those elements in a deformed portion of the tire between a wheel and a footprint region where the tire contacts a surface can assume a significantly reduced portion of the load, if any. This causes web elements in other portions of the interconnected web to operate in tension to support the load.

This application is a continuation of U.S. patent application Ser. No.12/506,169, filed Jul. 20, 2009, the entire contents of which is herebyincorporated by reference.

This invention was made, in part, with United States government supportawarded by the United States Army Research Laboratory under contractnumbers W911NF-06-2-0021 and W911QX-08-C-0034. Accordingly, the UnitedStates may have certain rights in this invention.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present application is directed to a tire, and more particularly, toa non-pneumatic tire.

2. Description of the Related Art

Non-pneumatic, or airless, tires (NPT) have historically been comprisedlargely of an entirely solid substance. These solid tires made the riderather uncomfortable for passengers and caused greater damage to thesuspension of a vehicle, which had to compensate for the lack of “give”in a solid tire. Eventually, it was found that putting pressurized airin tires created a more comfortable ride. However, along with theiradvantages, pneumatic tires still possess some drawbacks.

The material that encloses standard pneumatic tires is susceptible toleaking the pressurized air it tries to withhold. This occurs both vialeakage around the wheel rim, and on a smaller scale, when the rubber ofthe tire absorbs the oxygen. As a result, loss of pressure causes thetire to flatten in the area where the load is applied, subjecting alarger portion of the tire to the load with every revolution, andleading to quicker degradation of the tire. Furthermore, a tire reliantupon pressurized air is susceptible to being punctured leading to rapidrelease of the pressurized air.

Focusing on fuel efficiency, safety and ride comfort, several attemptshave been made to address the problems associated with pneumatic tireswhile retaining their advantages over solid non-pneumatic tires. By wayof example, U.S. Published Application 2006/0113016 by Cron, et al., andassigned to Michelin, discloses a non-pneumatic tire that itcommercially refers to as the Tweel™. In the Tweel™, the tire combineswith the wheel. It is made up of four parts that are eventually bondedtogether: the wheel, a spoke section, a reinforced annular band thatsurrounds the spoke section, and a rubber tread portion that contactsthe ground.

Other alternatives to standard pneumatic tires have been attempted,including making solid tires out of polyurethane instead of rubber andsuspending reinforcement materials within the polyurethane duringmolding. Another alternative is to use internal ribs made of athermoplastic that are subsequently reinforced with glass fibers. Athird alternative is to use an electroactive polymer that is capable ofchanging shape when an electrical current is applied. This allows thetire to change shape or size based upon road conditions by using theautomobile's electrical system.

In addition, embodiments of non-pneumatic tires which incorporate aninterconnected web to support the tire load are disclosed in U.S.Publication No. 2008-0314486, the entire contents of which isincorporated by reference herein.

SUMMARY OF THE INVENTIONS

In accordance with at least one embodiment disclosed herein, anon-pneumatic tire can comprise an inner ring that attaches to a wheelhaving an axis of rotation, an outer ring, and an interconnected webbetween the inner ring and outer ring. The interconnected web can bemade of a material that is relatively stronger in tension than incompression such that the portion of the web between the wheel and afootprint region can either buckle or be subject to a significantlysmaller portion of the load, if any, while the rest of the load can bedistributed through the remaining portion of the interconnected web.

The interconnected web can be one of multiple possible forms. Theelements of the web can form multiple layers of interfitting generallypolygonal openings, such that there are at least two adjacent layers ofopenings spaced at different radial distances from each other whenviewed at any radial slice of the web. The openings of one layer can besimilarly shaped compared to the openings of at least one other layer,but they can also be shaped differently. In addition, the openings ofone layer can be similarly shaped to the other openings in that samelayer. Furthermore, while the openings of one layer can be similarlyshaped to the openings of another layer, they can be sized differently,such that the openings of a radially outer layer can be larger orsmaller than the openings of a comparatively radially inner layer.

At least one aspect of the embodiments described herein includes therealization that it would be advantageous to not only have aninterconnected web, but also an interconnected web with web elementswhich are shaped, curved, and/or made thicker or thinner depending onthe type of loading and/or buckling desired. Web elements which arecurved or made thicker or thinner in portions can provide added benefitto the non-pneumatic tire by facilitating buckling in one or moredirections.

Thus, in accordance with at least one embodiment disclosed herein, anon-pneumatic tire for supporting a load can comprise a generallyannular inner ring having an axis of rotation, a deformable generallyannular outer ring, and a flexible interconnected web extending betweenthe inner and the outer ring, the interconnected web comprising at leasttwo radially adjacent layers of web elements at every radialcross-section of the tire, the web elements defining a plurality ofgenerally polygonal openings and comprising at least one radial webelement that is angled relative to a plane that extends radially throughthe axis of rotation and at least one tangential web element that isgenerally transverse to the radial plane. The web elements can havefirst and second ends comprising connection points, the web elementextending radially in a curved manner between the first and second ends.A substantial amount of the load can be supported by a plurality of theweb elements working in tension.

In accordance with yet another embodiment disclosed herein, anon-pneumatic tire can comprise a generally annular inner ring thatattaches to a wheel, a generally annular outer ring, an interconnectedweb between the generally annular inner ring and the generally annularouter ring, and an axis of rotation. The interconnected web can define aplurality of openings circumferentially spaced around the tire andradially spaced at varying distances from the axis of rotation, so as tosupport a load by working in tension. The interconnected web cancomprise at least one web element having first and second ends definingconnection points, the web element extending radially in a curved mannerbetween the first and second ends.

In accordance with yet another embodiment disclosed herein, anon-pneumatic tire can comprise a generally annular inner ring thatattaches to a wheel, a generally annular outer ring, an interconnectedweb between the generally annular inner ring and the generally annularouter ring, and an axis of rotation. The interconnected web can define aplurality of openings circumferentially spaced around the tire andradially spaced at varying distances from the axis of rotation, so as tosupport a load by working in tension. The interconnected web cancomprise at least one web element, wherein the thickness of the at leastone web element decreases moving radially away from the center of thetire.

In accordance with yet another embodiment disclosed herein, anon-pneumatic tire can comprise a generally annular inner ring thatattaches to a wheel, a generally annular outer ring, an interconnectedweb between the generally annular inner ring and the generally annularouter ring, and an axis of rotation. The interconnected web can define aplurality of openings circumferentially spaced around the tire andradially spaced at varying distances from the axis of rotation, so as tosupport a load by working in tension. The interconnected web cancomprise at least one web element having more than one thickness alongits length.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the present embodiments will become moreapparent upon reading the following detailed description and withreference to the accompanying drawings of the embodiments, in which:

FIG. 1 is a front view of an undeformed non-pneumatic tire.

FIG. 2 is a front view of the non-pneumatic tire of FIG. 1 beingdeformed when subjected to a load.

FIG. 3 is a sectional perspective view of the undeformed non-pneumatictire taken along line 3-3 in FIG. 1.

FIG. 4 is a front view of another embodiment of an undeformednon-pneumatic tire.

FIG. 5 is a front view of still another embodiment of an undeformednon-pneumatic tire.

FIG. 6 is a front view of a further embodiment of an undeformednon-pneumatic tire.

FIG. 7 is a front view of yet another embodiment of an undeformednon-pneumatic tire.

FIG. 8 is a front view of another embodiment of an undeformednon-pneumatic tire.

FIG. 9 is a front view of still another embodiment of an undeformednon-pneumatic tire.

FIG. 10 is a front view of still another embodiment of an undeformednon-pneumatic tire.

FIG. 11 is a sectional view of a tread carrying portion attached to anon-pneumatic tire taken along line 11-11 in FIG. 2.

FIG. 12 is a sectional view of another tread carrying portion attachedto a non-pneumatic tire taken along line 11-11 in FIG. 2.

FIG. 13 is a sectional view of still another tread carrying portionattached to a non-pneumatic tire taken along line 11-11 in FIG. 2.

FIG. 14 is a perspective view of an embodiment of an undeformednon-pneumatic tire with circumferentially offset segments.

FIG. 15 is a sectional perspective view of the undeformed non-pneumatictire taken along line 15-15 in FIG. 14.

FIG. 16 is a front view of the undeformed non-pneumatic tire as viewedfrom the line 16-16 in FIG. 14.

FIG. 17 is a perspective view of the non-pneumatic tire of FIG. 1.

FIG. 18 is an enlarged, cutaway view of the interconnected web of thenon-pneumatic tire of FIG. 17.

FIG. 19 is a cut-away front view of yet another embodiment of anundeformed non-pneumatic tire, with web portions which have a generallycurved profile.

FIG. 20 is a cut-away front view of yet another embodiment of anundeformed non-pneumatic tire, with web portions which become thinnerand increase in number moving away from the center of the tire.

FIG. 21 is a cut-away front view of yet another embodiment of anundeformed non-pneumatic tire, with web portions which have varyingthicknesses.

FIG. 22 is a cross sectional view of an embodiment of the shear layer ofa non-pneumatic tire.

FIG. 23 is a cross sectional view of an embodiment of the shear layer ofa non-pneumatic tire.

FIG. 24 is a perspective view of an embodiment of a non-pneumatic tireincorporating a cylinder and two wheel components.

FIG. 25 is an exploded view of the embodiment of FIG. 24.

FIG. 26 is a perspective view of an embodiment of a non-pneumatic tireincorporating a cylinder and wheel plate.

FIG. 27 is an exploded view of the embodiment of FIG. 26.

FIG. 28 is a perspective view of an embodiment of a non-pneumatic tire,including a sidewall integrated with the interconnected web.

FIG. 29 is a left side view of the sidewall in FIG. 28.

FIG. 30 is a perspective view of an embodiment of a non-pneumatic tire,including a sidewall integrated with the interconnected web.

FIG. 31 is a left side view of the sidewall in FIG. 30.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1, 2 and 3 illustrate an embodiment of a non-pneumatic tire 10having certain features and advantages according to an embodiment of thepresent invention. In the illustrated embodiment, the non-pneumatic tire10 comprises a generally annular inner ring 20 that engages a wheel 60to which tire 10 is mounted. The wheel 60 has an axis of rotation 12about which tire 10 spins. The generally annular inner ring 20 comprisesan internal surface 23 and an external surface 24 and can be made ofcross-linked or uncross-linked polymers. In one embodiment, thegenerally annular inner ring 20 can be made of a thermoplastic materialsuch as a thermoplastic elastomer, a thermoplastic urethane or athermoplastic vulcanizate. In another embodiment, the generally annularinner ring 20 can be made of rubber, polyurethane, and/or other suitablematerial. In this application, the term “polymer” means cross-linked oruncross-linked polymers.

For smaller applied loads, L, the generally annular inner ring 20 can beadhesively engaged with wheel 60 or can undergo some chemical structurechange allowing it to bond to the wheel 60. For larger applied loads, L,the generally annular inner ring 20 can be engaged to the wheel 60 viasome form of a mechanical connection such as a mating fit, although amechanical connection can be used for supporting smaller loads as well.The mechanical engagement can provide both the wheel 60 and thegenerally annular inner ring 20 with extra strength to support thelarger applied load, L. In addition, a mechanical connection has theadded benefit of ease of interchangeability. For example, if thenon-pneumatic tire 10 needs to be replaced, generally annular inner ring20 can be detached from wheel 60 and replaced. The wheel 60 can then beremounted to the axle of the vehicle, allowing the wheel 60 to bereusable. In another embodiment, the inner ring 20 can be connected tothe wheel 60 by a combination of a mechanical and adhesive connection.

With continued reference to FIGS. 1, 2 and 3, the non-pneumatic tire 10further comprises a generally annular outer ring 30 surrounding aninterconnected web 40 (discussed below). The outer ring 30 can beconfigured to deform in an area around and including a footprint region32 (see FIG. 2), which decreases vibration and increases ride comfort.However, since in some embodiments the non-pneumatic tire 10 does nothave a sidewall, the generally annular outer ring 30, combined with theinterconnected web 40, can also add lateral stiffness to the tire 10 sothat the tire 10 does not unacceptably deform in portions away from thefootprint region 32.

In one embodiment, the generally annular inner ring 20 and a generallyannular outer ring 30 are made of the same material as interconnectedweb 40. The generally annular inner ring 20 and the generally annularouter ring 30 and the interconnected web 40 can be made by injection orcompression molding, castable polymer, or any other method generallyknown in the art and can be formed at the same time so that theirattachment is formed by the material comprising the inner ring 20, theouter ring 30 and the interconnected web 40 cooling and setting.

As shown in FIGS. 1, 2 and 3, the interconnected web 40 of non-pneumatictire 10 connects the generally annular inner ring 20 to the generallyannular outer ring 30. In the illustrated embodiment, the interconnectedweb 40 comprises at least two radially adjacent layers 56, 58 of webelements 42 that define a plurality of generally polygonal openings 50.In other words, with at least two adjacent layers 56, 58, a slicethrough any radial portion of the non-pneumatic tire 10 extending fromthe axis of the rotation 12 to the generally annular outer ring 30passes through or traverses at least two generally polygonal openings50. The polygonal openings 50 can form various shapes, some of which areshown in FIGS. 4-10 and 19-21. In many embodiments, a majority ofgenerally polygonal openings 50 can be generally hexagonal shape withsix sides. However, it is possible that each one of the plurality ofgenerally polygonal openings 50 has at least three sides. In oneembodiment, the plurality of generally polygonal openings 50 are eithergenerally hexagonal in shape or hexagonal in shape circumferentiallyseparated by openings that are generally trapezoidal in shape, as can beseen in FIG. 1, giving interconnected web 40 a shape that can resemble ahoneycomb.

A preferred range of angles between any two interconnected web elements(moving radially from the tread portion of the tire to the wheel) can bebetween 80 and 180 degrees (See, for example, the web elements of FIG.1). Other ranges are also possible.

With continued reference to the illustrated embodiment of FIGS. 1, 2 and3, the interconnected web 40 can be arranged such that one web element42 connects to the generally annular inner ring 20 at any given point orline along the generally annular inner ring 20 such that there are afirst set of connections 41 along the generally annular inner ring 20.Likewise, one web element 42 can connect to the generally annular outerring 30 at any given point or line along an internal surface 33 of thegenerally annular outer ring 30 such that there are a second set ofconnections 43 along the generally annular outer ring 30. However, morethan one web element 42 can connect to either the generally annularinner ring 20 or to the generally annular outer ring 30 at any givenpoint or line.

As shown in FIGS. 4-10, the interconnected web 40 can further compriseintersections 44 between web elements 42 in order to distribute appliedload, L, throughout the interconnected web 40. In these illustratedembodiments, each intersection 44 joins at least three web elements 42.However, in other embodiments, the intersections 44 can join more thanthree web elements 42, which can assist in further distributing thestresses and strains experienced by web elements 42.

With continued reference to FIGS. 4-10, the web elements 42 can beangled relative to a radial plane 16 containing the axis of rotation 12that also passes through web element 42. By angling the web elements 42,applied load, L, which is generally applied perpendicular to the axis ofrotation 12, can be eccentrically applied to the web elements 42. Thiscan create a rotational or bending component of an applied load on eachweb element 42, facilitating buckling of those web elements 42 subjectedto a compressive load. Similarly situated web elements 42 can all beangled by about the same amount and in the same direction relative toradial planes 16. Preferably, however, the circumferentially consecutiveweb elements 42, excluding tangential web elements 45, of a layer ofplurality of generally polygonal openings 50 are angled by about thesame magnitude but measured in opposite directions about radial planessuch that web elements 42 are generally mirror images about radial plane16 of one another.

Each of the openings within the plurality of generally polygonal tubularopenings 50 can, but is not required, to be similar in shape. FIG. 7,for example shows a first plurality of generally polygonal openings 50that is different in shape from a second plurality of generallypolygonal openings 51. In this embodiment, at least one opening of thefirst plurality of general polygonal openings 50 can be smaller than atleast one opening of the second plurality of generally polygonalopenings 51. FIG. 7 also shows that each generally polygonal opening inthe first plurality of generally polygonal openings 50 has an innerboundary 57 spaced a radial distance, R₁, from axis of rotation 12 andeach generally polygonal opening in the second plurality of generallypolygonal openings 51, has a second inner boundary 59 spaced a radialdistance, R₂, which can be greater than R₁, from axis of rotation 12.

The number of openings 50 within the interconnected web 40 can vary. Forexample, the interconnected web 40 can have five differently sizedopenings patterned 16 times for a total of 80 cells, such as in FIG. 1.In yet other embodiments, other numbers of openings 50 can be used otherthan 16. For example, in preferred embodiments the interconnected web 40could include between 12-64 patterns of cells. Other numbers outside ofthis range are also possible.

As shown in FIGS. 7 and 8, openings in a radially inner layer 56 can besimilarly shaped as compared to those in a radially outer layer 58 butcan be sized differently from those openings such that the generallypolygonal openings 50 increase in size when moving from opening toopening in a radially outward direction. However, turning to FIG. 10, asecond plurality of generally polygonal openings 51 in a radially outerlayer 58 can also be smaller than those in a first plurality ofgenerally polygonal openings 50 in a radially inner layer 56. Inaddition, the second plurality of generally polygonal openings can beeither circumferentially separated from each other by a third pluralityof generally polygonal openings 53 or can be greater in number than thefirst plurality of generally polygonal openings 50, or it can be both.

As noted above, FIGS. 1-9 show several variations of a plurality ofgenerally polygonal openings 50 that are generally hexagonally shaped.As shown, these openings can be symmetrical in one direction or in twodirections, or, in another embodiment, they are not symmetrical. Forexample, in FIG. 1, radial symmetry planes 14 bisect several of theplurality of generally polygonal openings 50. Those openings aregenerally symmetrical about radial symmetry planes 14. However,interconnected web 40 of tire 10 can also be generally symmetrical as awhole about radial symmetry planes. In comparison, a second plurality ofgenerally polygonal openings 14 can be generally symmetrical aboutsimilar radial symmetry planes 14. In addition, as shown in FIGS. 7-8, asecond plurality of generally polygonal openings can be generallysymmetrical about lines tangent to a cylinder commonly centered withaxis of rotation 12, providing a second degree of symmetry.

The web elements 42 can have significantly varying lengths from oneembodiment to another or within the same embodiment. For example, theinterconnected web 40 in FIG. 7 comprises web elements 42 that aregenerally shorter than web elements of the interconnected web shown inFIG. 6. As a result, interconnected web 42 can appear denser in FIG. 7,with more web elements 42 and more generally polygonal openings 50 in agiven arc of tire 10. In comparison, FIGS. 9 and 10 both showinterconnected webs 40 which web elements 42 substantially vary inlength within the same interconnected web. In FIG. 9, radially inwardweb elements 42 are generally shorter than web elements 42 locatedcomparatively radially outward. However, FIG. 10 shows radially inwardweb elements 42 that are substantially longer than its radially outwardweb elements 42. As a result, interconnected web 40 of FIG. 9 appearsmore inwardly dense than interconnected web 42 of FIG. 10.

With continued reference to FIG. 10, an interconnected web 40 is shownsuch that web elements 42 define a radially inner layer 56 of generallypolygonal openings 50 that is significantly larger than a radially outerlayer 58 of generally polygonal openings 50. Radially inner layer 56 cancomprise alternating wedge-shaped openings 55 that may or may not besimilarly shaped. As shown, second plurality of generally polygonalopenings 51 can be separated from first plurality of generally polygonalopenings 50 by a generally continuous web element 42 of interconnectedweb 40 spaced at a generally constant radial distance from axis ofrotation 12. The generally continuous, generally constant web element 42can assist in providing further stiffness to non-pneumatic tire 10 inregions that are resistant to deformation.

With reference back to FIG. 2, the combination of the geometry ofinterconnected web 40 and the material chosen in interconnected web 40can enable an applied load, L, to be distributed throughout the webelements 42. Because the web elements 42 are preferably relatively thinand can be made of a material that is relatively weak in compression,those elements 42 that are subjected to compressive forces may have atendency to buckle. These elements are generally between the appliedload, L, that generally passes through axis of rotation 12 and footprintregion 32 and are represented as buckled section 48 in FIG. 2.

In one embodiment, some or all of the web elements 42 can be providedwith weakened (e.g., previously bent) or thinned sections such that theweb elements 42 preferentially bend and/or are biased to bend in acertain direction. For example, in one embodiment, the web elements arebiased such that they bend generally in an outwardly direction. In thismanner, web elements do not contact or rub against each as they buckle.In addition, the position of the weakened or thinned portion can be usedto control the location of the bending or buckling to avoid suchcontact.

When buckling occurs, the remaining web elements 42 may experience atensile force. It is these web elements 42 that support the applied loadL. Although relatively thin, because web elements 42 can have a hightensile modulus, E, they can have a smaller tendency to deform butinstead can help maintain the shape of the tread carrying layer 70. Inthis manner, the tread carrying layer 70 can support the applied load Lon the tire 10 as the applied load L is transmitted by tension throughthe web elements 42. The tread carrying layer 70, in turn, acts as anarch and provides support. Accordingly, the tread carrying layer 70 ispreferably sufficiently stiff to support the web elements 42 that are intension and supporting the load L. Preferably a substantial amount ofsaid applied load L is supported by the plurality of said web elementsworking in tension. For example, in one embodiment, at least 75% of theload is supported in tension, in another embodiment at least 85% of theload is supported in tension and in another embodiment at least 95% ofthe load is supported in tension. In other embodiments, less than 75% ofthe load can be supported in tension.

Although the generally annular inner ring 20, the generally annularouter ring 30, and the interconnected web 40 can be comprised of thesame material, they can all have different thicknesses. That is, thegenerally annular inner ring can have a first thickness, t_(i), thegenerally annular outer ring can have a second thickness, t_(o), and theinterconnected web can have a third thickness, t_(e). As shown in FIG.1, in one embodiment, the first thickness t_(i) can be less than thesecond thickness t_(o). However, the third thickness, t_(e), can be lessthan either first thickness, or the second thickness, t_(o). Thisillustrated arrangement is presently preferred as a thinner web element42 buckles more easily when subjected to a compressive force whereas arelatively thicker generally annular inner ring 20 and the generallyannular outer ring 30 can advantageously help maintain lateral stiffnessof non-pneumatic tire 10 in an unbuckled region by better resistingdeformation.

The thickness, t_(e), of web elements 42 can vary, depending onpredetermined load capability requirements. For example, as the appliedload, L, increases, the web elements 42 can increase in thickness,t_(e), to provide increased tensile strength, reducing the size of theopenings in the plurality of generally polygonal openings 50. However,the thickness, t_(e), should not increase too much so as to inhibitbuckling of those web elements 42 subject to a compressive load. As withchoice of material, the thickness, t_(e), can increase significantlywith increases in the applied load L. For example, in certainnon-limiting embodiments, each web element 42 of interconnected web 40can have a thickness, t_(e) between about 0.04 inch and 0.1 inch thickfor tire loads of about 0-1000 lbs, between about 0.1 and 0.25 inchthick for loads of about 500-5000 lbs, and between 0.25 and 0.5 inchthick for loads of about 2000 lbs or greater. Those of skill in the artwill recognize that these thicknesses can be decreased or increased inmodified embodiments.

In addition to the web elements 42 that are generally angled relative toradial planes 16 passing through axis of rotation 12, the interconnectedweb 40 can also include tangential web elements 45, as shown in FIGS.1-9. The tangential web elements 45 can be oriented such that they aregenerally aligned with tangents to cylinders or circles centered at axisof rotation 12. The tangential web elements 45 are preferred becausethey assist in distributing applied load L. For example, when theapplied load L, is applied, the web elements 42 in a region above axisof rotation 12 are subjected to a tensile force. Without the tangentialweb elements 45, interconnected web 40 may try to deform by having theother web elements 42 straighten out, orienting themselves in agenerally radial direction, resulting in stress concentrations inlocalized areas. However, by being oriented in a generally tangentialdirection, the tangential web elements 45 distribute the applied load, Lthroughout the rest of interconnected web 40, thereby minimizing stressconcentrations.

Staying with FIGS. 1-9 the plurality of generally polygonal openings 50are shown wherein each one of said plurality of generally polygonalopenings 50 is radially oriented. As noted above, the generallypolygonal openings 50 can be oriented such that they are symmetricalabout radial symmetry planes 14 that pass through axis of rotation 12.This arrangement can facilitate installation by allowing tire 10 tostill function properly even if it is installed backwards because itshould behave in the same manner regardless of its installedorientation.

As shown in FIG. 1, the generally annular outer ring 30 can have aradially external surface 34 to which a tread carrying layer 70 isattached. Attachment can be done adhesively or using other methodscommonly available in the art. In addition, as seen in FIG. 11-13, thetread carrying layer 70 can comprise embedded reinforcing belts 72 toadd increased overall stiffness to the non-pneumatic tire 10 wherein theembedding of the reinforcing belts 72 is accomplished according tomethods commonly available in the art. Reinforcing belts 72 can be madeof steel or other strengthening materials.

FIGS. 11-13 show several possible examples of the arrangement of thereinforcing belts 72 in tread carrying layer 70. FIG. 11 is a versionshowing a tread 74 at a radial outermost portion of the tire 10. Movingradially inwardly are a plurality of reinforcing belts 72 a, a layer ofsupport material 76, which forms a shear layer, and a second pluralityof reinforcing belts 72 b. In this embodiment, the reinforcing belts 72a, 72 b are arranged so that each belt is a generally constant radialdistance from axis of rotation 12.

Turning to the embodiment of FIG. 12, a tread carrying layer 70 similarto that of FIG. 11 is shown. However, the embodiment of FIG. 12 showsthe layer of support material 76 being approximately bisected in agenerally radial direction by at least one transverse reinforcing belt72 c. Support material 76 can be a rubber, polyurethane or similarcompound that as a footprint is formed by the tire, the support material76 between the reinforcing belts 72 is subjected to a shear force. Thus,the support layer 76 provides the tread carrying layer 70 with increasedstiffness.

The tread carrying layer 70 of FIG. 13 resembles that of FIG. 11 butcomprises two additional groupings of reinforcing belts 72. In additionto the generally radially constant plurality of reinforcing belts 72 a,72 b, the tread carrying layer 70 in FIG. 13 includes transversereinforcing belts 72 d, 72 e. The transverse reinforcing belts 72 d, 72e include at least one reinforcing belt 72 d proximate a longitudinallyinner surface and at least one reinforcing belt 72 e proximate alongitudinally outer surface, such that reinforcing belts 72 a, 72 b, 72d, 72 e generally enclose layer of support material 76 in a generallyrectangular box shape.

The reinforcing belts 72 and the support material 76 as described abovegenerally form a shear layer. As a footprint is formed by the tire, thesupport material 76 between the reinforcing belts is subjected to ashear force. Thus, the support layer 75 provides the tread carryinglayer with increased stiffness.

In one embodiment, the shear layer (support material) 76 has a thicknessthat is in the range from about 0 inches (i.e., no shear layer) to about1 inch think (as measured along a radius extending from the axis ofrotation). In other heavy load applications, the shear layer 76 can havea thickness greater than 1 inch.

The interconnected web 40, the generally annular inner ring 20 and thegenerally annular outer ring 30 can be molded all at once to yield aproduct that has a width or depth of the finished non-pneumatic tire.However, the interconnected web 40, the generally annular inner ring 20and the generally annular outer ring 30 can be manufactured in steps andthen assembled as seen in the embodiments of FIGS. 14-16. In thesefigures, each segment 18 has an interconnected web 40 having the samepattern as the non-pneumatic tire 10 of FIG. 1.

FIG. 14 shows a perspective view of an embodiment where the tire 10comprises a plurality of segments 18. Each segment 18 can have agenerally uniform width, W_(s), but they can also have different widthsin modified embodiments. The segments 18 can be made from the same moldso as to yield generally identical interconnected webs 40, but they canalso be made from different molds to yield varying patterns ofinterconnected webs 40. In addition, as seen in FIGS. 14, 15 and 16,segments 18 can be circumferentially offset from one another so that aplurality of generally polygonal openings 50 a of one segment 18 is notgenerally aligned with a plurality of similarly-shaped generallypolygonal openings 50 b of a radially adjacent segment 19. The segmentscan alternate so that every other segment 18 is generally aligned. Inanother embodiment, the segments do no alternate. FIG. 15 shows anembodiment having seven segments 18, where the first, third, fifth andseventh segments 18 a, 18 c, 18 e and 18 g are generally aligned witheach other, the second, fourth and six segments 18 b, 18 d, and 18 f aregenerally aligned with each other, but the two groups of segments arenot generally aligned as a whole. In addition, FIG. 15 is a cutaway viewshowing two radially adjacent segments 18, 19 that are not generallyaligned. This stacking orientation can help with buckling around thefootprint region 32, can decrease vibration and noise, and can providegreater torsional stiffness to non-pneumatic tire 10.

In some embodiments, a non-pneumatic tire 10 can be made more or lessstiff by adding or removing layers and/or segments of interconnectedwebbing 40. For example, and with continued reference to FIG. 14, anadditional segment 18 can be added to the tire 10 to increase itsstiffness, bringing the total number of segments to eight. Theadditional segment 18 can be added during production of the tire, or, ifthe tire has already been produced, the segment 18 can be addedmechanically, such as by fasteners, adhesion, or other processes. Insome embodiments, a tire 10 can start with one segment and/or layer ofwebbing, and if greater stiffness is required, a second segment and/orlayer can be added to the tire 10. If a smaller tire less stiff tire isdesired, a segment and/or layer can be removed. The addition and removalof segments and/or layers can be beneficial, for example, in the contextof a large trailer which experiences a wide range of loading. When thetrailer is expected to experience a heavier load, the tire 10 can bereinforced by adding another segment or segments 18 of interconnectedwebbing 40, and if desired, the segment or segments 18 can subsequentlybe removed at a later point. In such an embodiment, tire 10 can comprisea modular system in which the use can be provided with several segments.For light loads, only one or a few segments are placed on to the wheel60 of the vehicle. Then with larger loads additional segments can beslipped onto or otherwise attached to the wheel.

The choice of materials used for interconnected web 40 may be animportant consideration. In one embodiment, the material that is usedwill buckle easily in compression, but be capable of supporting therequired load in tension. Preferably, the interconnected web 40 is madeof a cross-linked or uncross-linked polymer, such as a thermoplasticelastomer, a thermoplastic urethane, or a thermoplastic vulcanizate.More generally, in one embodiment, the interconnected web 40 canpreferably be made of a relatively hard material having a durometermeasurement of about 80A-95A, and in one embodiment 92A (40D) with ahigh tensile modulus, E, of about 21 MPa or about 3050 psi or in otherembodiments between about 3000 psi to about 8000 psi. However, tensilemodulus can vary significantly for rubber or other elastomericmaterials, so this is a very general approximation. In addition,durometer and tensile modulus requirements can vary greatly with loadcapability requirements.

The polymer materials discussed above for the interconnected web 40, theinner ring 20, and/or the outer ring 30 can additionally includeadditives configured to enhance the performance of the tire 10. Forexample, in one embodiment, the polymer materials can include one ormore of the following: antioxidants, light stabilizers, plasticizers,acid scavengers, lubricants, polymer processing aids, anti-blockingadditives, antistatic additives, antimicrobials, chemical blowingagents, peroxides, colorants, optical brighteners, fillers andreinforcements, nucleating agents, and/or additives for recyclingpurposes.

Other advantages can be obtained when using a polymer material such aspolyurethane to make non-pneumatic tire 10 instead of the rubber oftraditional tires. A manufacturer of the illustrated embodiments canonly need a fraction of the square footage of work space and capitalinvestment required to make rubber tires. The amount of skilled labornecessary can be significantly less than that of a rubber tire plant. Inaddition, waste produced by manufacturing components from a polyurethanematerial can be substantially less than when using rubber. This is alsoreflected in the comparative cleanliness of polyurethane plants,allowing them to be built in cities without the need for isolation, soshipping costs can be cut down. Furthermore, products made ofpolyurethane can be more easily recyclable.

Cross-linked and uncross-linked polymers, including polyurethane andother similar non-rubber elastomeric materials can operate at coolertemperatures, resulting in less wear and an extended fatigue life oftire 10. In addition, the choice of materials for interconnected web 40and outer ring 30 can significantly decrease rolling resistance, leadingto about a 10% decrease in fuel consumption. Polyurethane has betterabrasion resistance and, therefore, better tread wear than a traditionalrubber tire and, unlike rubber, it is inert, making it resistant tooxidization or reaction with other materials that make rubber harden oreven crack.

In another embodiment shown in FIGS. 17 and 18, the interconnected web40 comprises web elements 42 that also contain strengthening components46 such as carbon fibers, KEVLAR®, or some additional strengtheningmaterial to provide additional tensile strength to the interconnectedweb 40. Properties of the strengthening components 46 for certainembodiments can include high strength in tension, low strength incompression, light weight, good fatigue life and an ability to bond tothe material comprising interconnected web 40.

With reference to FIG. 19, further embodiments of the interconnected web40 of tire 10 can comprise at least one web element 42 which isintentionally curved. For example, each web element 42 can have a firstend comprising a first connection point and a second end comprising asecond connection point, with the web element 42 extending radiallybetween the first and second ends in a curved manner. Each of theconnection points can join together one or more of the web elements 42and/or the inner or outer ring 20, 30. In some embodiments, the webelements 42 can be curved in directions which facilitate buckling of theweb 40 during loading of the tire. For example, and as illustrated inFIG. 19, the web elements 42 can form generally polygonal structureswherein the web elements forming the structures alternate between havinggenerally concave and convex curvatures. Other configurations of curvedweb elements 42 are also possible. In some embodiments, the curvedprofiles of the web elements 42 can aid in keeping the elements 42spatially separated from one another, thereby reducing the likelihood ofthe elements 42 contacting one another during buckling. Furthermore, thecurved profiles of the web elements 42 can also inhibit noise andvibration which may otherwise result from having straight, linear webelements 42 throughout the web 40.

With reference to FIG. 20, in some embodiments the interconnected web 40can comprise web elements 42 which generally become thinner as they moveradially away from the inner ring 20 and center of the tire 10. Thethinning nature of the web elements 42 can, in some embodiments, reducethe amount of material used in the web 40 as compared with the web 40 ofthe embodiments described above, thereby allowing for a morelight-weight tire 10. In some embodiments, and with continued referenceto FIG. 20, the web elements 42 can not only decrease in thickness asthey move closer to the outer edge of the tire, but also increase innumber. This increase in the number of web elements 42 can lead tosmaller openings, or gaps, between the ends of the web elements 42 whichcontact the outer ring 30. This reduction in opening size can inhibitnoise and vibration in the tire 10. In some embodiments, at least aportion of the web elements 42 can also generally be curved similar tothe web elements 42 shown in FIG. 19.

With reference to FIG. 21, in some embodiments at least one of theinterconnected web elements 42 can have a varying thickness along itslength. The varying thicknesses can facilitate directional buckling ofindividual web elements 42 in one or more given directions, and/orfacilitate buckling on certain web elements 42 but not others. Forexample, one of the web elements 42 positioned generally along a planetransverse to a radius of the tire 10 can have a thinner portion 47along a center portion of the web element 42. The thinner portion 47 canbe bounded by two identical thicker portions of the web element 42,giving the web portion 42 a generally symmetrical shape. The thinnerportion 47 of the web element 42 can facilitate directional buckling ineither direction (i.e. buckling of the web element in a concave mannertowards the outer ring 30, or in a convex manner towards the inner ring20). In contrast, and with continued reference to FIG. 21, other webelements 42 in the web 40 can have notches or grooved portions whichgive the web element 42 a non-symmetrical shape. The thinner portions 47formed in these web elements 42 can facilitate buckling in one directionmore so than another, based on their generally non-symmetrical nature.Other shapes and configurations of notches and/or thinner portions 47are also possible.

Furthermore, and with continued reference to FIG. 21, in someembodiments a varying thickness in the web element 42 can aid inreducing what would otherwise be a high stress area within the web 40.For example, the web element 42 can include portions of varyingthickness to absorb stresses imposed during tensioning of the webelements during loading, thereby increasing the amount of stress the webelement 42 can withstand prior to fracture or failure. For example, theweb element 42 can have a thicker cross-section in the area where itexperiences the greatest tensile loading, and a thinner cross-section inother areas.

With reference back to the tread and shear layers, in the embodimentsshown in FIGS. 22 and 23, a crowned (FIG. 22) or rounded configuration(FIG. 23) of the components of the tread layer 70 can be utilized toprevent or reduce excessive drag on the edges of the tread and shearlayer 70 during steering or cornering of the vehicle.

Thus, for example, and with reference to FIG. 22, in at least oneembodiment the tread carrying layer 70 can comprise inner belt layers 78a and 78 b. The belt layer 78 a can have a larger width than the beltlayer 78 b, giving the tread carrying layer 70 a generally crowned orrounded shape. A layer of support material 76 can be placed between thebelt layers 78 a and 78 b.

With reference to FIG. 23, in at least another embodiment the treadcarrying layer 70 can comprise belt layers 80 a and 80 b. Both beltlayers 80 a and 80 b can be curved in order to give the tread carryinglayer 70 a generally crowned or rounded shape. Again, a layer of supportmaterial 76 can be placed between belt layers 80 a and 80 b.

The tread carrying layer 70 of FIGS. 11-13, 22 and 23 described abovecan be manufactured similar to pneumatic tires. For example, in oneembodiment, each layer of the tread carrying layer can be manufacturedseparately in rolls. The thicknesses of the rolls can vary. In at leastone embodiment, some of the rolls can be rubber, while other rolls cancomprise a steel belting that is coated in a rubber compound andconfigured for a particular belt angle for a particular tire. Each ofthe rolls can be brought to a tire building machine, and wrapped ontothe machine in a particular order. The last layer can generally comprisea thick layer of rubber to be used as the exterior tread for the tire.

After wrapping each layer, the entire assembly can be brought to a mold.The outer diameter of the mold can have the reverse pattern of the treadengraved in it. The mold can be heated to a temperature that allows therubber to easily deform and/or flow. The assembly can be set in themold, and pressure can be applied from the inside to force the treadagainst the outer wall of the mold, which converts the thick outer layerinto a patterned tread. The assembly can sit within the mold under heatand pressure for a specified period of time, allowing the rubber layersto vulcanize and generally transform from several individual layers intoone solid layer.

Once a tread carrying layer has been manufactured as described above,the tread carrying layer 70 can be connected to the interconnected web40. Various methods can be used. For example, at least one arrangementcomprises overmolding the interconnected web 40 directly onto theradially inwardly facing surface of the tread carrying layer 70. Anadhesive can be sprayed onto the inside diameter of the tread carryinglayer 70 and outside diameter of the tire's wheel 60. In one embodiment,a mold can then be filled with liquid urethane. The adhesive on thetread layer 70 and wheel 60 of the tire 10 can form a bond with theurethane. Once the urethane cures and stiffens, the interconnected web40 will be molded to both the tread carrying layer 74 and tire wheel 60.

In another embodiment, the interconnected web 40 can first be madeseparately in its own mold. The outside diameter of the interconnectedweb 40, or the generally annular outer ring 30, can be formed so that itis slightly larger than the inside diameter of the tread carrying layer70. An adhesive can be applied to the outside diameter of theinterconnected web 40. The interconnected web 40 can then be temporarilycompressed so that it can be placed into the tread carrying layer 70.Once the interconnected web is positioned correctly, the compression onthe interconnected web 40 can be removed. The interconnected web 40 canthen spread out and contact the tread carrying layer 70. This method canreduce the residual tension (caused by shrinking of the web material asit cures) that might occur by molding the interconnected web 40 andattaching it to the tread carrying layer 70 at the same time asdiscussed above.

As mentioned above, the tire 10 can be coupled to the wheel 60 of avehicle. In at least one embodiment, a generally cylindrical componentcan fasten to the non-pneumatic tire's wheel 60. For example, withreference to FIGS. 24 and 25, an embodiment of a non-pneumatic tire 110can comprise a hollow metal (or other material) cylinder 112 configuredfor attachment to an existing HMMWV or other vehicle's wheel components114, 116. The cylinder 112 can include a flanged portion 118 extendingtowards the interior hollow portion of the cylinder 112. The flange 118can have holes 119 a which align with holes 119 b in the wheelcomponents 114, 116, thereby facilitating attachment of the cylinder 112and wheel 114, 116 by bolts or other fasteners (not shown). While theembodiment shown discloses a flange 118 that extends circumferentiallyaround the interior of the cylinder 112, in other embodiments the flange118 can extend around only a portion of the interior of the cylinder112. In yet other embodiments, there can be a plurality of flangesspaced apart around the interior of the cylinder 112.

At least a portion of cylinder 112 can be coupled to the generallyannular inner ring 20 as described above. Thus, an interconnected web 40and a generally annular outer ring 30, such as any of those shown inFIGS. 1-21, can be attached to the exterior, or radially outwardlyfacing surface, of cylinder 112 via molding, adhesion, or other methodsof attachment. The cylinder 112, the interconnected web 40, the innerring 20, and the generally annular outer ring 30 can then be attached tothe wheel 112, 114.

The tire configuration of FIGS. 24 and 25 provides an advantage in tireservicing and replacement. For example, the cylinder 112 and wheelcomponents 114, 116 can easily be removed from one another by removingthe bolts or other fasteners. Once the bolts are removed, the tire 10can quickly be serviced, and/or parts of the tire 10 can quickly andeasily be replaced.

With reference to FIGS. 26 and 27, another embodiment of a non-pneumatictire 210 can comprise a metal (or other material) cylinder 212. Cylinder212, much like cylinder 112 of the preceding embodiment, can include aflange 216 with holes configured for attaching cylinder 212 with wheelplate 214. Just as with cylinder 112, the inner ring 20, theinterconnected web 40 and the generally annular outer ring 30, such asany of those shown in FIGS. 1-21, can be attached to the radiallyoutwardly facing surface of cylinder 212 via molding, adhesion, or othermethods of attachment. The single metal wheel plate 214 can quickly andeasily be removed from the rest of the tire in order to service the tireor replace parts.

In yet another embodiment, the interconnected web and the generallyannular outer ring, such as any of those shown in FIGS. 1-21, can bedirectly attached to an existing wheel rim (not shown) without use of acylinder such as cylinder 112 or 212. Thus, instead of removing anybolts and replacing or servicing different parts of the tire, the tirecan simply be discarded when it has worn down.

Additionally, in yet another embodiment, an interconnected web can bedirectly engaged by a wheel, tread carrying layer, or both. For example,a wheel and tread carrying layer can either or both comprise dovetailjoints. The wheel and tread carrying layer can then be inserted into amold with the material comprising the interconnected web filling thejoints. In this case, the generally radially outwardly facing surfacesof the wheel comprise the generally annular inner surface of the tire,and the generally radially inwardly facing internal surface of the treadcarrying layer comprises the generally annular outer ring. Therefore,when the interconnected web sets, the interconnected web is directlyengaged, obviating the need to bond or otherwise affix theinterconnected web to the generally annular outer ring.

Non-pneumatic tires, including those that use an interconnected web asdiscussed above, can also incorporate the use of a sidewall or someother structure capable of covering and protecting the interconnectedweb 40 and tire 10. Use of a sidewall helps to ensure that debris,water, or other material does not enter the tire, including theinterconnected web area, and interfere with the tire's functionality andperformance. The sidewall can also help prevent damage to the web fromprojectiles or other debris.

With reference to FIGS. 28 and 29, a sidewall 310 can be attached to orintegrated with an interconnected web 40. In at least one embodiment,the sidewall 310 can be adhered directly to at least one side of theinterconnected web 40. The sidewall 310 can be entirely flat when viewedfrom its side, as illustrated in FIG. 29, such that it can be bondeddirectly to the edges of each or some of the interconnected web element42 exposed along the outside of the tire 10. The sidewall 310 can bemanufactured separately as one piece and then adhered to theinterconnected web 40, or the sidewall can be integrated directly intothe interconnected web's molding during production of the web 40.

With continued reference to FIGS. 28 and 29, the sidewall 310 can coverall, or only a portion of, the side of the interconnected web 40. Byattaching or integrating a sidewall 310 onto at least a portion of theinterconnected web 40, debris or other material can be prevented fromentering the interconnected web area of the tire 10 and interfering withthe web elements 42.

The sidewall 310 can be made from the same material as that of theinterconnected web 40, or the material can be different, such as rubber.In some embodiments, the material for both the interconnected web 40 andsidewall 310 is cast polyurethane. Additionally, in some embodiments thesidewall 310 can have a lower stiffness than that of the interconnectedweb elements 42. By having a lower stiffness, the sidewall 310 asillustrated in FIGS. 28 and 29 will generally not support any of theloads acting on the tire 10. Instead, the sidewall 310 can bend or flexduring loading in the areas between the interconnected web elements 42,allowing the interconnected web elements 42 to continue supporting theloads acting on the tire 10. In other embodiments, the sidewall 310 cansupport a load.

In an additional embodiment, and with continued reference to FIGS. 28and 29, the sidewall 310 can be adhered to or integrated with theinterconnected web 40 only near the generally annular inner ring 20 andthe generally annular outer ring 30. In such embodiments, the sidewall310 is not adhered to or integrated with some of the interconnected webelements 42 located between the generally annular inner ring 20 andgenerally annular outer surface 30. This allows sidewall 310 the freedomto flex and bend in the region between the generally annular inner 20and the generally annular outer rings 30, instead of only in those areasbetween the interconnected web elements 42.

With reference to FIGS. 30 and 31, an additional embodiment of asidewall 410 can have a generally “domed” or flexed shape, as opposed tothe flat shape of sidewall 410 as shown in FIG. 29. In this embodiment,the sidewall 410 can be adhered to or integrated with the interconnectedweb 40 as discussed above near both the generally annular inner ring 20and the generally annular outer ring 30. The “domed” shape of thesidewall 410, as illustrated in FIG. 31, biases the sidewall 410 todeform in a prescribed direction (i.e. away from the web 40), as opposedto buckling or deforming in towards the web 40 and interconnected webelements 42. Just as with the previous embodiments, the sidewall 410 andinterconnected web 40 can be made of the same material, or differentmaterials. In some embodiments, the interconnected web material 40 iscast polyurethane, and the sidewall 410 rubber.

In yet additional embodiments, the sidewalls 310, 410 described abovecan be made separate from the interconnected web, and be removable fromthe tire for servicing and/or replacement. For example, the sidewall310, 410 can be held in place adjacent the interconnected web 40 by aflange or flanges encircling the tire 10. The flanges (not shown) can bemade from material having low stiffness so as to prevent the flangesfrom interfering with the functionality and performance of theinterconnected web elements 42. The flanges can be adhered to orintegrated with the interconnected web 40 or other portions of the tire10. In at least some embodiments, the sidewall can slide out from thegrip of the flanges. In yet other embodiments, the flanges can bend orflex, allowing the sidewall to be inserted or removed. In yet otherembodiments, the sidewall can be flexible enough to bend and to beinserted into the stationary flanges.

In yet additional embodiments, instead of an actual wall along theside(s) of the interconnected web 40, the interconnected web 40 can befilled partially or wholly with filler, for example, a foam material. Inat least one embodiment, the foam can comprise polyurethane foam. Byfilling the interconnected web 40 with foam or similar material, debriscan be prevented from entering the areas between the interconnected webelements 42, which can substantially interfere with the tire'sfunctionality and performance. At the same time, the foam can beflexible. Thus, the foam itself generally will not support any loads onthe tire, instead allowing the tire's interconnected web elements tocontinue supporting the loads. In addition, in other modifiedembodiments, the filler can be used to support some of the load. Asmentioned above, non-foam materials can also be used.

In yet additional embodiments, non-pneumatic tires can incorporatesidewalls similar to pneumatic tires. The sidewalls can be vulcanized tothe tread portion of the generally annular outer ring and additionallymounted to the rim of the wheel after the interconnected web has beenformed.

Sidewall thicknesses can vary, depending on factors including, but notlimited to, the expected applied loads the tire will experience duringuse, as well as material strength and flexibility. For example, in atleast one embodiment, a sidewall comprised of rubber can have athickness of approximately 0.09375″. In at least some embodiments, thethickness of the sidewall can also vary across each individual sidewall.

Advantageously, the embodiments of a non-pneumatic tire described aboveexhibit many of the same performance characteristics as traditionalpneumatic tires. For example, the non-pneumatic tire can demonstrate ageneral ride quality and traction similar to current pneumatic tires.The non-pneumatic tire 10 can also have costs, weight, load supportingcapability and tread life similar to current pneumatic tires.

However, the non-pneumatic tires of the embodiments described hereindemonstrate several advantages over standard pneumatic tires. Forexample, in addition to virtually eliminating blowouts and flat tires,the ability of the generally annular outer ring 30 and theinterconnected web 40 to deform in an area around footprint region 32 asshown in FIG. 2 reduces the stresses placed on wheel 60 when hitting abump, pothole, or similar obstacle, thereby making non-pneumatic tire 10and wheel 60 less susceptible to damage. Without relying on air pressureto maintain its functionality, interconnected web 40 of non-pneumatictire 10 can also be better able to withstand damage caused byprojectiles. If a portion of interconnected web 40 is damaged, theapplied load L, which is generally applied perpendicular to axis ofrotation 12, can be transferred to the remaining elements so that avehicle relying on non-pneumatic tires 10 is not immediately disabled.In addition, because non-pneumatic tire 10 cannot be over- orunder-inflated, footprint region 32 can remain generally constant,improving fuel efficiency as compared to traditional pneumatic tires.

The generally annular outer ring 30 combined with interconnected web 40can display higher lateral stiffness compared to standard pneumatictires, especially in the embodiment in which the tread carrying layer 70is attached. Therefore, while general ride quality can be similar tostandard pneumatic tires, non-pneumatic tire 10 can achieve improvedcornering ability. The non-pneumatic tire 10 can also require lessmaintenance by obviating the need to check and maintain air pressure.

Additionally, a major advantage of using a non-pneumatic tire comparedto a standard tire is eliminating flat tires. If a portion of the web iscompromised, the load will be redistributed through other elements ofthe web by virtue of the fact that the web is interconnected, prolongingthe life of the tire. In addition, by not carrying any significant loadalong a footprint region where the tire contacts a surface, a smootherride results since the non-pneumatic tire is less susceptible to shockand vibration.

Besides its benefits over traditional pneumatic tires, non-pneumatictire 10 can exhibit multiple advantages over other non-pneumatic tires.Most of these other tires have solid rim and a solid tire section andare in production for low-speed applications. In comparison to thesetires, the non-pneumatic tire 10 can be significantly lighter. Theinterconnected web 40 can allow non-pneumatic tire 10 to absorb impactssignificantly better, resulting in a more comfortable ride. In addition,other non-pneumatic tires are not usable at high speeds due to theamount of vibration that is generated. Some conventional non-pneumatictires work by placing the portion of the tire that is between theapplied load L and the contact surface in compression. This causes thatsection of the tire and its internal structure to deform under the load.When the body to which the tire is attached is not in motion, thisportion of the tire remains deformed under the static load. Over time,this can lead to semi-permanent deformation of the tire causingdecreased performance, increased noise vibration and worse fuelefficiency, among other things. In contrast, buckled section 48 carriesvery little, if any, load so the tire can remain statically deformed fora while and not experience any appreciable semi-permanent deformation.

In comparison to other tension-based non-pneumatic tires, tire 10 candemonstrate even further benefits. Non-pneumatic tire 10 can experiencesmaller stresses and strains under loading conditions than othertension-based non-pneumatic tires. By allowing air to flow through thetire 10 and around web elements 42, the design of interconnected web 40can result in less heat generation as well as less fatigue, prolongingthe life of tire 10. The ability of interconnected web 40 to bucklearound footprint region 32, thereby causing less reactive force whenpassing over an obstacle, can also result in less vibration and a betterride. Despite the ability of interconnected web 40 to buckle, it canalso be relatively stiff when compared to the internal structure ofother tension-based non-pneumatic tires. This can result in less noisebeing generated, resulting in a quieter ride. It can also causenon-pneumatic tire 10 to experience better starting and stoppingperformance.

Example

In one non-limiting example embodiment, a non-pneumatic tire 10possesses the interconnected web 40 of the configuration shown in FIGS.1 and 2. Tire 10 has a radius of about 9.5 inches and wheel 60 has aradius of about 4⅜ inches.

In general, the force required for buckling of a column is governed bythe equation: F_buckling=(KELIπ̂2)/l̂2 where K=a constant whose valuedepends on how the ends of the column are affixed, E=tensile modulus,I=the area moment of inertia, and l=the unsupported length of thecolumn.

If each web element 42 of interconnected web 40 is modeled as its ownthin column, the radially innermost elements will be fixed at one endand free to move laterally at another end. In this example, K=¼

In this example, the interconnected web 40 and the generally annularouter ring 30 are made of a similar material having a tensile modulus,E, of about 21 MPa or 3050 psi.

Tire 10 can be about 8 inches wide. As noted above, in preferredembodiments, each web element 42 of interconnected web 40 can be betweenabout 0.04 inch and 0.1 inch thick for tire loads of about 0-1000 lbs,between about 0.1 and 0.25 inch thick for loads of about 500-5000 lbs,and between 0.25 and 0.5 inch thick for loads of about 2000 lbs orgreater. A thickness of about 0.08 inch will be used for this example.In this case, the area moment of inertia, I=(w*ĥ3)/12 where w=the widthof each web element 42, 8 inches and h=the thickness, 0.08 inch.Therefore, I is about 0.000341 in̂4.

Using the tire and wheel radii mentioned above, and observing thepattern of interconnected web 40 as seen in FIGS. 1 and 2, each webelement 42 can have an approximate length of about (9.5″-4.375″)/4, orapproximately 1.28 inch.

Based on these numbers, F_buckling=(KEIπ̂2)/l̂2=about 1.59 lbs. Inaddition, web elements 42 of interconnected web 40 are angled withrespect to a radial direction to facilitate buckling, which can furtherdecrease F_buckling.

In this application, non-pneumatic tire 10 is subjected to a load, L, ofabout 250 lbs. Load, L, is distributed throughout web elements 42 suchthat the entire load, L, is not borne by a single web element, 42.However, the web elements 42 most directly aligned with the direction ofload, L, should bear the greatest portion of the load. Since L issignificantly larger than F buckling, elements 42 of interconnected web40 that are subjected to a compressive force will buckle and not supportload, L.

While the foregoing written description of embodiments of the inventionenables one of ordinary skill to make and use what is consideredpresently to be the best mode thereof, those of ordinary skill willunderstand and appreciate the existence of variations, combinations, andequivalents of the specific exemplary embodiments and methods herein.The invention should therefore not be limited by the above describedembodiment and method, but by all embodiments and methods within thescope and spirit of the invention as claimed.

1. A non-pneumatic tire for supporting a load comprising: a generallyannular inner ring having an axis of rotation; a deformable generallyannular outer ring; and a flexible interconnected web extending betweensaid inner and said outer ring, the interconnected web comprising atleast two radially adjacent layers of web elements at every radialcross-section of said tire, the web elements defining a plurality ofgenerally polygonal openings and comprising at least one radial webelement that is angled relative to a plane that extends radially throughthe axis of rotation and at least one tangential web element that isgenerally transverse to the radial plane; wherein at least one of theweb elements has a first end comprising a first connection point, and asecond end comprising a second connection point, the web elementextending radially in a curved manner between the first and second ends;wherein a substantial amount of said load is supported by a plurality ofsaid web elements working in tension.
 2. A non-pneumatic tire accordingto claim 1, wherein the web elements gradually become thinner movingradially away from the center of the tire.
 3. A non-pneumatic tireaccording to claim 1, wherein at least one of the web elements hasvarious thicknesses along its length.
 4. A non-pneumatic tire accordingto claim 1, further comprising a tread carrying layer affixed to aradially external surface of said outer ring, said tread carrying layerbeing sufficiently stiff to support said web elements working intension.
 5. A non-pneumatic tire according to claim 1, wherein saidplurality of generally polygonal openings comprises a first plurality ofgenerally polygonal openings having a first shape and a second pluralityof generally polygonal openings having a second shape different fromsaid first shape.
 6. A non-pneumatic tire according to claim 5, whereinat least one of said first plurality of generally polygonal openings andat least one of said second plurality of generally polygonal openingsare traversed when moving in any radially outward direction from saidaxis of rotation.
 7. A non-pneumatic tire according to claim 5, whereineach of said first plurality of generally polygonal openings has a firstinner boundary spaced at a first radial distance and each of said secondplurality of generally polygonal openings has a second inner boundaryspaced at a second, greater radial distance.
 8. A non-pneumatic tireaccording to claim 7 wherein at least one generally polygonal opening ofsaid first plurality of generally polygonal openings is larger than atleast one generally polygonal opening of said second plurality ofgenerally polygonal openings.
 9. A non-pneumatic tire according to claim1, wherein one web element engages said inner ring at a given locationwith its first connection point.
 10. A non-pneumatic tire according toclaim 1, wherein one web element engages said outer ring at a givenlocation with its second connection point.
 11. A non-pneumatic tireaccording to claim 1, wherein a connection point joins at least threeweb elements.
 12. A non-pneumatic tire according to claim 1, whereinsaid inner ring has a first thickness, said outer ring has a secondthickness, and said web elements have a third thickness, said thirdthickness being smaller than said first thickness or said secondthickness.
 13. A non-pneumatic tire according to claim 1, furthercomprising web elements that extend in a substantially radial directionwith respect to the axis of rotation.
 14. A non-pneumatic tire accordingto claim 1, wherein each one of said plurality of generally polygonalopenings is radially oriented.
 15. A non-pneumatic tire according toclaim 1, wherein each one of said plurality of generally polygonalopenings has at least 3 sides.
 16. A non-pneumatic tire according toclaim 1, wherein said plurality of generally polygonal openings aregenerally hexagonally shaped.
 17. A non-pneumatic tire according toclaim 1, further comprising a plurality of joined segments each having awidth narrower than a width of said tire.
 18. A non-pneumatic tireaccording to claim 17 wherein a first joined segment iscircumferentially offset from an adjoining segment.
 19. A non-pneumatictire according to claim 17, wherein a first joined segment has aninterconnected web that is substantially similar to an interconnectedweb of a second joined segment.
 20. A non-pneumatic tire according toclaim 1, wherein a relatively radially inner layer of said plurality ofgenerally polygonal openings comprises alternating generallywedge-shaped openings.